-at least one metric century every month;
-at least one imperial century every month;
I've found, goals like these to be the best way to build consistent cycling and if you aim for these shorter goals you will often end the year with much more mileage than you though you would. The problem with an annual goal is that if something happens, like illness or injury then you can end up trying to make up for lost ground and possibly end up injured or ill again or despondent if you fall short. Goals help you improve but can become a millstone instead of a milestone if they are too vague to keep you motivated in the short and long term.
The great thing with the goals above, is that if you get those centuries out of the way early in the month, you'll often squeeze more in to stay ahead for a rainy day and before you know it you have a head of momentum up and can often exceed the original goals, rather than be always chasing the big faraway annual number.
Saying that, those who ride for the pure joy of it without a care as to how far or how long are probably the happiest - for the rest of use we prob need the help of these little motivations to drag us out on days when we'd otherwise take the Lazy option.
Whatever the goals, best of luck to everyone.